I know these planes uses air cycle machine rather than refrigeration machine to provide cold pressurized air (11 psi). I know ACM are powered by hot bleed air and that most airliners use 2 or 3 packs that consist of turbine/compresor, primary/secondary air to air heat exchanger, moisture separator and catalystic converter to remove harmfull ozone. Trim air is used to provide different output temperatures to different zones.Then I read something about electric powered recirculation fans mounted overhead and under floor. They should recirculate cabin air through manifold system, but please someone explain how is this done. I aslo read that first bleed air cooling is done in heat exchanger that is mounted inside engine so engine fan cold air stream precooles the hot bleed air. Is this done only for packs or also for pneumatics. I gues both takes bleed air from same manifold?

I know these planes uses air cycle machine rather than refrigeration machine to provide cold pressurized air (11 psi). I know ACM are powered by hot bleed air and that most airliners use 2 or 3 packs that consist of turbine/compresor, primary/secondary air to air heat exchanger, moisture separator and catalystic converter to remove harmfull ozone. Trim air is used to provide different output temperatures to different zones.Then I read something about electric powered recirculation fans mounted overhead and under floor. They should recirculate cabin air through manifold system, but please someone explain how is this done. I aslo read that first bleed air cooling is done in heat exchanger that is mounted inside engine so engine fan cold air stream precooles the hot bleed air. Is this done only for packs or also for pneumatics. I gues both takes bleed air from same manifold?

The recirc fans simply pull air from the cabin interior back into remixing with the fresh air coming from the packs.The precooler is usually in the engine pylon. It is done for the entire bleed air system. Air going to packs or anti-ice or anything else that may use bleed air is broken off into their separate paths downstream of the precooler.

Air going to packs or anti-ice or anything else that may use bleed air is broken off into their separate paths downstream of the precooler.

So one must emphasize that this 'pre-cooled' air is still quite hot. It is hot enough that it can be used for anti-ice.

So one must emphasize that this 'pre-cooled' air is still quite hot. It is hot enough that it can be used for anti-ice.

Yes, it would typically be around 300 degrees celsius.

The recirc fans simply pull air from the cabin interior back into remixing with the fresh air coming from the packs.

ECS have three mayor tasks:*must pressurised the cabin (since ECS can't enrich outside air O2 %, this pressure must be between 700-900 mbar)*must provide fresh breathable air (with 200mbar partial O2 pressure and CO2 values less than 4%)*must maintain safe cabin temperatures (18-30

Did I do anything wrong? It seems you block the topic!

What do you mean, "blocked?" :( Maybe it's just that no one has anything more to say on the topic... :(

Man, it is boring as hell, partial pressures, consumption of O2 per human body, etc. If you think you have nothing else to do but to write this stuff .. keep on going, no one is goingto 'block' you. But bear in mind your audience will be limited. You are also on a wrong forum -you should be on a heating/AC/pneumatics forum.

Man, it is boring as hell, partial pressures, consumption of O2 per human body, etc. If you think you have nothing else to do but to write this stuff .. keep on going, no one is goingto 'block' you. But bear in mind your audience will be limited. You are also on a wrong forum -you should be on a heating/AC/pneumatics forum.

I think this is pretty interesting, although it may be boring to some people. Nothing in this world appeals all people. Way to be nice and respectful btw...